<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>特殊符号</title>
</head>

<body>
  <p>
    <!-- &lt表示< &gt表示> -->
    &lt;html权威指南&gt;
  </p>
  <p>
    你好&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;html
    <br>
    你好&emsp;&emsp;&emsp;&emsp;&emsp;&emsp;&emsp;html
  </p>
</body>

</html>